Process and apparatus for centrifuging



Jan. 1, 1935.

J. BERGE PROCESS AND APPARATUS FOR CENTRIFUGING Filed Sept. 1', 1952 2 Sheets-Sheet l IPJVENTOR ullem Barge ORNEYS Jan. 1, 1935. J. BERGE I Q PROCESS AND APPARATUS FOR CENTRIFUGING Filed se t. 1, 1932 ZSheets-Sheet 2 INVEN'rbR Julian Barge I Patented Jan. 1, 1935 r I r UNITED STATES PATENT, OFFICE PROCESS AND APPARATUS FOR C ENTRIFUGING Julien Berg, Tirlemont, Belgium, assignor to Raninerie Tirlemontoise, Societe Anonyme, Tirlemont, Belgium, a corporation Application September 1, i932, Serial No. 631,318 In Germany July 9, 1931 Claims. (01. 127 -20) This invention pertains to the general class in a pasty state, such discharge is made more of processes and apparatus for the separation of diificult unless means are provided to regulate liquids from solids and particularly to the class and/or prevent such evaporation. of processes and apparatus for the centrifugal When the invention is employed with the 5 separation thereof. ordinary centrifuge not operating with the high 5 The invention pertains more particularly to centrifugal forces of my above mentionedpatent, the regulation and/or prevention of the evaporaan increase in the degree of separation of syrup .tion of the volatile constituents of the liquids or mother liquor is afforded without washing beespecially during the rotation of the materials cause of the regulation and/or prevention of the to be separated in the basket of a centrifuge. drying influence of circulating-air. 10

I This affords a regulation and/or prevention of The process and apparatus of my above menchanges in viscosity of the adhering liquid mattioned copending application is one means of ter. accomplishing'the desired results.

The invention will be described in connection My invention herein comprises another means with the manufacture of sugar. However, it is of accomplishing the desired results. 15

to be understood that it may be applied to the A feature of this invention comprises the conmanufacture of other products, particularly those trol of the temperature and/or relative humidity that are obtained by crystallization from mother of the air which circulates through the sugar wall liquor. in the centrifuge basket.

In the manufacture of sugar, sugar crystals A further feature of the invention comprises 20 are crystallized from mother liquor, the mixture the conditioning of such air and a close control of 1 being known as massecuite. Thesugar crystals the same in accordance with the condition, and have considerable quantities of mother liquor particularly the temperature, of the materials adhering to the same. to-be centrifuged.

The latter is also true of raw sugar from which A further feature of the invention comprises 25 only a portion of mother liquor has been separated, certain details of construction, the arrangement leaving a thin film of syrup which adheres and combination of parts which, together with tenaciously to the surfaces of the sugar crystals. other features, will be more clearly understood Unless special precautions are taken such as upon reference to the drawings, in which those disclosed in my copending application, Fig.'1 is a diagrammatical illustration in ele- 30 Serial No. 453,886 filed May 20, 1930, a considervation of apparatus adapted to carry out the able flow of air takes place through the wall of process; sugar in the basket of the revolving centrifuge. Fig.2 is a diagrammatical illustration in ele- This flow of air prior to my present invention vation of another form of apparatus for carrying evaporated water from the adhering syrup or out the process; 5 1

mother liquor and resulted in a certain degree Fig. 3 is a diagrammatical illustration in eleof drying of the syrup or mother liquor causing vation of another form of apparatus for carrying the same to become more viscous and to adhere out the process; and even more tenaciously to the surfaces of the sugar Fig. 4 is a view illustrating the invention apcrystals. In some instances the syrup or mother plied to another type of centrifuge. 40 liquor may be driedto such an extent as to form Referring more particularly to Fig. 1 of the a hard lacquer-like coating around the indi-' drawings, at 10 is shown a centrifuge which may vidual crystals or around groups of crystals. be of any type or construction. The type of Prior to y invention s s d in my Patent centrifuge shown is for the purpose of illustra- No. 1,775,38 dated September 9, 1930, it was imtion. Centrifuge 10 is illustrated as comprising 45 DOSSible to completely Separate sy up or moth r an enclosed casing 11 having a dome-shaped porliq o f Sugar Crystals Without Washing the tion 12 at its top and a discharge door 13 at its crystals i t centrifuge. T e invention disbottom. The revolving basket is illustrated at .14. closed in y pa above'referred 190 ad D S- The air under ordinary conditions enters the hassible such separation without a washing operaket through the open top 15 and/or the open 50 tion. The higher centrifugal forces employed, bottom 16 and passes out through the perforated however, increase the flow of air, and consecylindrical wall 17 into the space 18 between quently the rate of evaporation, and although the the wall 1'7 and the casing 11..' From here the invention of the above mentioned patent will air, unless it is withdrawn for instance by means discharge syrup or mother liquor even though it is which I shall subsequently describe, will return 55 to the inside of basket 14 through the openings illustrated at 15 and/or 16. A continuous circulation is thus set up which would have a drying effect unless my invention is applied.

For the purpose of regulating the temperature and/or relative humidity of the air which is caused to flow through basket 14 outwardly through the wall 17 thereof and thus through the sugar wall illustrated diagrammatically at 19, I may employ any type of air conditioning apparatus with or without its many refinements such as air cleaners, etc.

The apparatus disclosed in the drawings comprises a blower or similar means illustrated at 21 for the circulation of air which it withdraws from space 18 by way of pipe 22, through a closed system comprising an air heater 23, an air humidifier 24 and a return pipe 25 which leads to dome 12 from which the air flows back into space 18 through the basket 14.

The air heater 23 may obviously be of any construction. Heater 23 is illustrated as comprising an enclosure 27 provided with a steam coil 28 supplied by a pipe 29 in which is a valve 30 of the weight regulated type, the weight being shown at 31. The volume of steam delivered to the coil 28 and consequently the temperature of the air passing through the enclosure 27 is regulated by means of a thermostatically controlled valve 32 which controls the operation of a hydraulic motor illustrated at 33. Motor 33 takes up and lets out end 34 of cable 35 attached to its piston 36. The other end 37 of cable 35 is attached to weight 31. The taking up and letting out of end 34 of cable 35 by the movement of piston 36 regulates the opening of the valve 30 and in turn the volume of steam delivered to coil 28, and consequently the temperature of the air flowing through air heater 23.

The thermostat by means of which the valve 32 is controlled may be placed in contact with the sugar either while in the centrifuge basket 14 or preferably before its introduction into said basket. This thermostat may also be inserted in the pipe 25 so as to be controlled by the temperature of the air delivered to dome 12. The latter arrangement might be preferred particularly if the temperature of the sugar to be centrifuged is more or less constant.

A humidostat 38 inserted in pipe 40 controls valve 39 and is therefore adapted to regulate the relative humidity of the air passing through pipe 40 from spray chamber 41' to eliminator 42 by its control of the motor42a. Motor 4211 is adapted to take up and let out end 43 of cable 44 attached to'its piston 45. The other end 46 of cable 44 is attached to weight 47 of valve 48 which is inserted in the water supply pipe 49 which delivers water to the atomizing mechanism illustrated at 50.

The motors 33 and 42a illustrated are of the oil pressure operated piston and cylinder type and are supplied with oil under pressure from the common oil pump illustrated at 52.

Oil flowing from motor 33 must pass through pipe 54'and valve 32 in order to escape from the cylinder of motor 33. The rate of escape, therefore, controls the position of the piston and consequently the position of valve 30. The oil upon escaping returns through pipe 55 to container 56 from which oil is drawn by the pump 52. In other words, the position of piston 36 is regulated .by the rate of flow of oil through valve 32.

Motor 42a, and consequently the position of its piston 45, is regulated by the flow of oil through pipe 58 and valve 39. Pipe 59 returns the escaped oil to the container 56. The position of the valve 39 which is determined by humidostat 38 thereby regulates the position of piston 45 and in turn the degree of opening of valve 48, and consequently the relative humidity of the air passing through spray chamber 41.

In operation air pump 21 sucks air from the space 18 and delivers it to air heater 23 in which heat is supplied in the required amount so that it will be delivered to dome 12 at the desired temperature. From air heater 23 the air is delivered to spray chamber 41- of humidity regulator 24 in which its humidity is regulated to' an extent depending upon the desired degree of saturation or relative humidity desired. The air then passes the humidostat 38 which is inserted in pipe 40 and passes down into eliminator 42 in which any globules of excess water, etc. are removed. The air from eliminator 42 passes into dome 12 through pipe 25 and from dome 12 passes through the basket 14, back into space 18.

Humidostat 38 might also be placed in pipe 25.

Regulation of the circulation of the air through the system is afforded by a valve 62 connected across pipes 25 and 22 and a valve 63 in pipe 22. Valve 62 provides a short circuit for the air by permitting the air to return to pump 21 without passing through the centrifuge, and valve 63 providesa regulation for the amount of air which may be drawn from the space 18. Consequently, upon regulation of the valve 62 and/or valve 63 a complete control of the volume of air passing through the centrifuge is afforded.

The form of apparatus illustrated in Fig. 2 is in all respects'similar to that illustrated in Fig. 1 except that suction pipe 122 does not communicate with space 18 but is open to the atmosphere, and space 18 is provided with a discharge opening leading to the atmosphere through pipe 65.

In operation the form shown in Fig. 2 does not re-circulate the air after it has once passed through the sugar-wall 19. Fresh air is sucked in through pipe 122 and may or may not be cleaned by cloth or viscous filters or otherwise.

After being heated in air heater 23 so that it will be delivered to dome 12 at the proper temperature, it is brought to the desired humidity in humidifier 24. Entrained water is removed by eliminator 42, and the air is then delivered to dome 12. After passing through the basket 14 into the space 13, the air escapes into the atmosphere through the pipe 65.

The form of apparatus shown in Fig. 3 is in all respects similar to that shown in Fig. 1 except that the pipe .125 leading from eliminator 42 does not deliver the conditioned air-to the dome 12 but delivers it to the conical bottom 66 of casing 11 from which point it finds its way up into the basket 14 from the bottom instead of from the top.

The centrifuge-illustrated is also open at the bottom.

' In Fig. 4 I have shown my invention applied to a well known centrifuge of'the continuously operable type comprising a casing 70, a revolving basket 71 having a horizontal axis 72, a feed pipe. 73, a discharge chute 74 and a scraping mech anism 75 for dislodging the centrifuged material for removal through chute 74. The casing 70 is entirelyclosed. Conditioned air is delivered to the interior of basket '71 through pipe 76 and the sugar wall.

removed through pipe 7'7 after passing through" 1,986,245 tion as applied to sugar massecuite which at the time of centrifuging has a temperature of, say,

50C. If the circulating air has a temperature lower than that of the sugar massecuite and is saturated with moisture, the air is warmed by its contact with the massecuite and thereby becomes less saturated or, in other words, its relative humidity is lower. The air will, therefore, exercise a certain drying influence upon the mother liquor or'syrup adhering to the sugar crystals.

Should the temperature of the circulating air be higher than that of the massecuite, the air is cooled by its contact with the massecuiteand thereby becomes supersaturated at its lower temperature. Therefore, the supersaturated air will give up a certain quantity of its moisture which will perform a washing operation and will tend to dissolve some of the sugar, particularly if the temperature drop is considerable. The resultant solution will be carried offwith the mother liquor or syrup in a manner similar to that of a washing operation.

On the other hand, should the circulating air be of the same temperature as that of the massecuite, that is 50 C. in the example above, and if it is saturated with moisture there will be no change of the temperature of the air as it passes through the massecuite or sugar wall and consequently no change in the saturated condition of the air. Nor will there be a change in the temperature of the massecuite or sugar as a'result of the flowing air. In the last instance the circulating air will exercise neither a drying nor a dissolving effect upon the massecuite or syrup nor on the crystals. The above example might be applied to raw sugar or any other product and obviously applies to any temperature.

With the apparatus shown and described the regulation of the air temperature and its relative humidity takes' place automatically. Any other apparatus mightbe employed or any other means might be substituted for the various elements shown.

The process makes it possible to separate mother liquor from crystals, adhering syrup-from raw sugar crystals, etc. with or without the use of high centrifugal forces and without shutting off the air flow such as described and claimed in my copending application above referred to.

Small leakages with this invention are of no moment inasmuch as leakages will merely result in the escape of conditioned air.

It will be seen that by varying the temperature and/or humidity of the circulating air it is possible to have a cycle of operations, for instance in using centrifuges not employing high centrifugal forces it might be desirable to separate asmuch syrup as possible with the air saturated and at the same temperature as the massecuite so as to have neither a drying nor a washing effect, next to saturate the air at a higher temperature so as to wash off the last vestiges of syrup from the sugar crystals, followed by a drop in air temperature and/ or relative humidity so as to dry the washed sugar crystals.

This could be used with high centrifugal forces if there should be any reason for it.

Any other cycle of operations or combination of operations or effects might be employed.

Having described my invention, it is obvious that any other type or form of air conditioning apparatus might be employed and applied to any other type of centrifuge or in any other manner for the purpose of regulating the viscosity of a liquid to be separated from solids.

Having described my invention, it is obvious that many other modifications may be made in the same within the scope of the claims without departing from the spirit thereof.

While the invention has been described in connection with the use of air, it is, of course, understood that any other suitable gas might be employed. This applies particularly to the closed system shown in Fig. 1'.

Although the invention has been described in connection with the form which employs the centrifugal action of the revolving basket to cause the air to fiow through the materials in the basket, it is to be understood that the flow through the basket might under some circumstances be altered or reversed, particularly if the pressure in space 18 can be maintained sufliciently low as to not interfere with the separation of the materials.

This application is a continuation in part of my copending application, Serial No. 621,501 filed July 8, 1932.

I claim: I

1. In a process of separating viscous material from solid material by centrifuging, said viscous material containing a volatile liquid, the steps which comprise conditioning a gas with vapor of said volatile liquid, enveloping a mass of said materials to be separated with said conditioned gas during the centrifuging operation, and controlling the relative saturation and temperature of said gas'to maintain the partial pressure of the vapor of said volatile liquid in the separating zone within a predetermined narrow range adjacent the point at which such partial pressure substantially equals that of the vapor pressure of said volatile liquid in said viscous material, while centrifuging said mass.

2. In a process of separating mother liquor from sugar crystals by centrifuging, the steps which comprise conditioning, air with water vapor, enveloping a mass of mother liquor and sugar crystals to be separated with said conditioned air during the centrifuging operation, and controlling the relative humidity and temperature of said air to maintain the partial pressure of the water vapor in the centrifuging zone within a predetermined narrow range adjacent the point at which such partial pressure substantially equals that of the vapor pressure of the 'water in said mother liquor, while centrifuging said mass.

3. The process of from sugar crystals which comprises centrifuging a mass of said mother liquor and sugar crys-' tals at a speed such that the centrifugal force developed is at least about 800 times the weight of the crystals, conditioning air with water vapor, enveloping said mass with said conditioned air during the centrifuging operation, and controlling the relative humidity and temperature of said air to maintain the partial pressure of the 'water vapor in the centrifuging zone substantially equal to the vapor pressure of the water in said mother liquor.

4. In an apparatus for centrifugally separating mother liquor from crystals, in combination, a centrifuge having a rotating basket adapted to contain a mass of mother liquor and crystals to be separated, means for conditioning a gas with vapor of a volatile constituent of 'said' mother liquor, comprising a humidifier and a heater, means for leading a gas through said humidifier and said heater to said centrifuge I and for circulating said' conditioned gas about separating mother liquor and through the walls of said basket, and means responsive to changes in the temperature of the mass of mother liquor and crystals for regulating said humidifier and said heater and thereby controlling the relative humidity and temperature of said gas to maintain the partial pressure of the humidifying vapor in the centrifuging zone within a predetermined narrow range rela-v tive to the vapor pressure of the volatile constituent of said mother liquor.

5. In an apparatus for centrifugally separating mother liquor from crystals, in combination, a centrifuge having a rotating basket adapted to contain a mass of mother liquor and crystals to be separated, means for conditioning a gas with vapor of a volatile constituent of said mother liquor, comprising a humidifier and a heater, means establishing a closed circuit for said gas through and between saidheater, said humidifier and said centrifuge, means for flowing gas through said circuit, and means responsive to changes in the temperature of the mass of mother liquor and crystals for regulating said humidifier and said heater and thereby controlling the relative humidity and temperature 'of said gas to maintain the partial pressure of the humidifying vapor in the centrifuging zone within a predetermined narrow range relative to the vapor pressure of the volatile constituent of said mother liquor.

JULIEN BERGE. 

